AITA for going no contact with my stepsister after she threatened to ruin my marriage because I’m not a woman?

I’ve been married to my husband for 8 months. We’re 27 and 29 and it has been amazing. We were both orphans and grew up together since we were kids, but we didn’t turn into a couple until a few years ago when we both started reflecting on what we really wanted from life. My in-laws are very happy to have me as a part of the family. They don’t really have any “in-laws issues” and we all got very close very fast. I adored my husband’s mother, who is just a sweetheart. She really took me under her wing and made sure I felt loved and comfortable.<br><br>Until I met her, I had the worst luck with stepsisters. My dad had one, and when I was young, I made contact with her to reconnect. She was an alcoholic junkie and tried to get me to be her kid’s dad when I was just 16. I was appalled and blocked her after my parents found out and told her never to contact me again. That was a disaster.<br><br>My husband and I got serious, made the leap, and got engaged. We were so excited to tell his family that we were going to get married. We were all ecstatic until he told his mom that he wanted me to keep my last name. He’d already been calling me his wife for over a year, and we’d already taken care of making me a beneficiary on all his policies and everything else. But apparently, this was an insult to his stepsister. His sister told the family that I was not the true wife, that I wasn’t a real woman, and that I was stealing her brother. My future in-laws were appalled, but she’d already spread so much drama and her own filth that no one believed it was that serious. I just completely ignored her. I didn’t want to create drama and I was upset for about two minutes and then I moved on. I didn’t need some jealous, bitter, crazy person to bring me down.<br><br>When I married my husband, she showed up uninvited and caused a scene when she found out I was keeping my birth name. She told everyone that the wedding was a sham and that I wasn’t a real wife, then stormed off. My husband’s mom paid for the entire honeymoon, and his sister got all bent out of shape about it, saying that she wanted to be the neemeristic wife and that I’d stole the hony moon, then tried to get my husband to come back to her. She tried to get into our room when we were on our honeymoon to tell him that she was pregnant, that if he didn't become a daddy with her, he'd be ruining his niece or nephew's life. My husband was livid that she even tried to get into his room, then told his sister that if she ever said a word against me again, she would never see or speak to him or his kids ever again.<br><br>After the wedding, I was constantly being watched. I was monitored, she was always lurking and spreading shit about me. She told people that I was having an affair with my husband’s boss when I wasn't doing anything of the sort. My husband was constantly having to defend me. He’s really a sweetheart, but this turned into a full time job. It never stopped. <br><br>Then, about two weeks before our wedding, she texted me that she had pictures of my father and his girlfriend "fucking" and that she would send them if I didn't start being a good stepsister. My dad’s wife is amazing and I adore her. I was so upset. I asked my husband what I should do and he told me to just block her and ignore her. But I was so angry and upset. I told him that if those pictures existed, she'd use them no matter what I did. He went beast mode and told his sister that she better have that text deleted and that he wanted her ass in court so fast it hurt or he’d disown her forever. I never heard from her again until a week after we got married and I was out with my friends having a great time and celebrating our honeymoon. She sent me a message with a link, telling me to open it. She'd hacked into my facebook and changed my profile picture to the pictures she'd stolen of my dad and his girlfriend. She wrote "This is what you are *too*" and I was so fucking pissed. I blocked her, told my husband, and I cut her off completely.<br><br>My husband’s mom told me she was so sorry for having such a horrible daughter, but that she couldn’t do anything to fix the relationship. I told her I was sorry, but that I didn't want to have anything to do with someone who'd try to sabotage my marriage and embarrass me. She told me she totally understood and that I didn't have to feel bad for protecting myself. My husband’s father called me and told me that his wife was right, and he was sorry his daughter was such a piece of shit. He gave me all his daughter’s social media accounts and told me where she worked, so I could block her from anywhere. He also said he would cut her off if she ever tried to contact me again and that he would disown her if she tried anything else on my family, especially my dad. I was really touched by them, and I love them so much.<br><br>Now, my husband’s sister has found my Instagram again, which I barely use, and has been sending me creepy messages like "your turn will come soon" and "I hope your husband loves you as much as I loved him" with these awful, disgusting emojis. I blocked her again, but it won’t last. She'll find another way in. My husband wants me to go nuclear and destroy her life, but I really don't want to. I don’t feel bad about what I did and I’m not going to apologize for it. He says she had it coming and she knew what she was doing when she started this and that I have every right to be upset. But he thinks I’m an asshole for trying to keep her out of my life.<br><br>AITA?